Princess Caroline wears the sapphires in Denmark, May 2004 (Pascal Le Segretain/Getty Images)

As September draws to a close, we’ve got one more celebration of the month’s spectacular birthstone! Here’s a look at the stunning cabochon sapphire suite owned by the Grimaldis of Monaco.

An official family portrait from Prince Rainier and Princess Grace’s wedding, April 1956; (L-R): John Kelly Jr., John Kelly Sr., Margaret Kelly, Princess Grace, Prince Rainier III, Princess Charlotte (wearing her sapphire necklace), Prince Pierre, and Princess Antoinette

The diamond and sapphire necklace and coordinating earrings were reportedly made by Cartier for Princess Charlotte of Monaco, Duchess of Valentinois. Charlotte was the mother of Prince Rainier III, and she wore the sapphire necklace for his wedding in April 1956. On this occasion, she wore the necklace with drop earrings.

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Here’s a closer look at the necklace, which features a large cabochon sapphire in the center and smaller sapphires interspersed with geometric diamond sections.

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This closer view shows that small sapphires are also included in those diamond spacer sections.

The sapphires are now worn by Princess Charlotte’s granddaughter, Princess Caroline of Monaco. They’ve been in her jewelry box for decades. You’ll note that Caroline generally wears the necklace with a pair of sapphire cabochon stud earrings, which feature a small diamond halo-style border. Those earrings seem to be ensuite with the necklace. In 1989, she wore them for an appearance at the Cannes Film Festival. Above, in March 1996, she wore the sapphires for the Rose Ball in Monaco.

She also wore the sapphires for the Red Cross Gala in August 1996, pairing them with a star-spangled gown.

Princess Caroline wears the sapphires in Denmark, May 2004 (CLAUS FISKER/AFP via Getty Images)

One of Caroline’s most prominent appearances in the sapphire demi-parure came in May 2004, when she wore them with the Brunswick Tiara for the wedding of Crown Prince Frederik and Crown Princess Mary of Denmark.

In June 2008, Caroline wore the earrings and necklace for a party in Paris in honor of the American Friends of the Louvre Museum.

Princess Caroline wears sapphires at the Red Cross Gala, August 2013 (VALERY HACHE/AFP via Getty Images)

Although Caroline usually wears the sapphire earrings and necklace together as a set, she sometimes wears them separately. At the Red Cross Gala in August 2013, she wore the sapphire and diamond earrings with other sapphire jewels, including two large rings and a stunning sapphire tennis bracelet.